Production of m-amino-p-cresol-methyl-ether



Patented Dec. 8, 1925.

UNITED STATES:

.v 1,564,214 PATENT: OFFICE.

CLARENCE G. DERICK, THOMAS H. LEAMING, AND WALTER M. RALPH, OE BUFFALO,

NEW YORK, ASSIGNORS TO NATIONAL ANILINE & CHEMICAL CO., INCq-OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PRODUCTION OF M-AMINOP-CRESOL-METHYL-ETHER.

No Drawing.

To all whom it may concern:

Be it known that we, CLARENCE G. DER- 10x, Trromxs H. LEAMING, and VVAL'rnR M. RALPH, citizens of the United States, I

such as will enable others skilledvin the art to which it appertains to make and use the same.

This invention relates to the production of m-amino-p-cresol methyl ether l-methyl- 2-amino-l-methoxy-benzene), from m-nitrop-cresol, (4-methyl-2-nitrophenol).

In the production ofm-nitro-p-cresol methyl ether from m-nitro-p-cresol, it has heretofore been proposed to convert the mnitro-p-cresol into m-nitro-p-cresol methyl ether by introducing the silver salt of the m-nitro-p-cresol gradually into methyl iodide diluted with ether, removing the silver iodide by filtration, and the excess ofmethyl iodide an ether by distillation, and to recover the m-nitro-p-cresol methyl ether by steam distillation. It has also been proposed to heat the potassium salt of the nitro-cresol with excess of methyl iodide in a closed vessel for a long period of time and at an elevated temperature of about 140 to 150 .C.

In the production of m-amino-p-cresol methyl ether from m-nitro-p-cresol methyl ether it has been proposed to efiect the reduction of the nitro group to the amino group by means of tin and hydrochloric acid.

These prior proposals, however, are expensive and are not well adapted for use in the commercial production of m-aminop-cresol methyl ether. The process of the present invention avoids the objections to these proposals, and enables the m-aminop-cresol methyl ether to be )roduced from m-nitro-p-cresol in a simp e and advantageous manner, and with good yield.

According to the present invention, the m-nitro-p-cresol is subjected to methylation to produce the nitro-cresol methyl ether, and the nitro-cresol methyl ether is then subjected to reduction to reduce the nitro grou to the amino group. The methylation 1s effected by means of dimethyl sulfate Application filed March 9,1920. Serial No. 364,428.

and alkali; while the subsequent reduction is effected with sodium disulfide, or-su1fur and sodium monosulfide;

The invention'will be further illustrated by the following more detailed description of a specific example thereof, the parts being by weight:

500 parts of cresol, and 153 parts of dimethyl sulfate, are charged in the order mentioned into. the reaction vessel, and a solution of51 parts of caustic soda in water is then run in slowly, the temperature being ,maintained at about 40 to,50 G; Since the nitro-cresol, the dimethyl sulphate, and the nitro-cresol methyl ether are all immiscible with water,

' good agitationis essential throughout the methylation in order to accomplish a thorough mixing of the reacting substances. After the caustic is all run in, the mixture is permitted to interact for a certain time, e. g., about 2 hours, and it is then heated at 100 C. a sufficient time todestroythe excess of methyl sulfate. The alkalinity of the solution should be maintained during the methylation.

The methylation can take place in the presence of varying amounts of water. Sufficient water shou d be present to facilitate the operations, while large quantities of water present no advanta e and are rather a disadvantage since they require the handling of larger volumes. The quantity of caustic soda should be sufiicient to decompose all of the dimethyl sulfate used.

The quantity of dimethyl sulfate should be at least that theoretically required to effect the methylation, that is, 1 mol, but a slight excess is desirable of both the dimethyl sulfate and the caustic soda, for example, an excess of from 10 to 25%. Even molecular proportions or a very slight excess of the imethyl sulfate maybe sufiicient, for example, -1 mol of the dimethyl sulfate and 1.10 mols of caustic soda.

An alternative method of effecting the methylation is to dissolve the nitrocresol in the requisite amount of dilute alkali, and gradually run in the dimethyl sulfate, while maintaining the temperature at around 40 to C. and agitating thoroughly; although we regard this alternative method as less advantageous thankthat above 'described.

The kettle used for the methylation may advantageously be provided with a reflux condenser so arranged that it can, be used as a straight condenser for distilling off any methyl alcohol that may result from any excess of dimethyl sulfate that ma be used, or that may be formed from the ium methyl sulfate.

After the methylation, the nitrocresol methyl other is subjected to reduction to reduce the nitro group to the amino group. This reduction can advanta eously be carried out in the same vessel used for the methylation and without isolation of the methyl ether. The hot mixture resulting from the methylation may thus be used without cooling, and the solid sodium sulfide (chip monosulfide) and sulfur gradually added with vigorous agitation, or a solution of the two as sodium disulfide may be added, the sulfide .being so added that a constant and vigorous, but not a violent, reaction will take place. If the sodium disulfide is added too rapidly, the reaction becomes violent, and the contents of the kettle are apt to boil over. The sulfide should accordingly be added sufficiently slowly, or the kettle provided with ,suflicient cooling means, to prevent the reaction from becoming too vi orous. \Vhen the sulfide is all in, a samp e is taken and subjected to steam distillation. If the temperature of solidification of the distillate indicates that the reduction is not complete, more sulfide is added, while still maintaining refluxing conditions, which are maintained during the entire reduction. When a sample of the product, upon steam distillation, shows the reduction to have proceeded far enough, the entire product is subjected to steam distillation and the aminocresol methyl ether thereby recovered. It should have a solidifying temperature of about 48-t0 50 C.

The amount of sodium sulfide used can be somewhat varied, and materially less amounts than that above indicated may suffice. The amount of sodium disulfide (or of sodium monosulfide and sulfur) may thus be about 1.5 mols for each mol of the nitrocresol methyl ether to be reduced. A large excess of the sulfide may not be objectionable, but likewise presents no advantage.

The steam distillation of the aminocresol methyl ether may be effected from the same kettle used for the methylation and reduction, and making use of the same condenser used as a reflux condenser during the reduction.

The following specific example will further illustrate a somewhat modified form of the process of the invention, using somewhat decreased amounts of reagents. The parts are by weight:

200 parts of water are introduced into an iron kettle, 152 parts of nitrocresol added,

and then 130 parts of dimethyl sulfate (100%). This mixture is subjected to vigorous agitation and 160 parts of B. caustic soda are added. The caustic soda is run in slowly while maintaining the temperature at from to until a permanent brilliant yellow color is produced, and the temperature is maintained until vthe methylation is complete, when any small remaining excess of dimethyl sulfate is decomposed by heating in the manner above described.

lVhile the solution is still hot, :1 solution of sodium disultide is gradually added, with good agitation and refluxing. The sodium disulfide solution may be prepared, for exam le, from 1200 parts of sodium monosul de chips), 300 parts of sulfur, and 2000 parts of water, the formation of the solution being promoted by heating with steam. At the end of the reduction, the aminocresol methyl ether is steam distilled.

In the reduction of the nitrocresol methyl ether, it is of importance to add the sodium disulfide solution to the mixture containing the nitrocresol methyl ether, rather than the reverse, inasmuch as the sodium disulfide solution is of a practically homo 'enous character, while the nitrocresol methyT ether mixture is not homogeneous.

If some of the nitrocresol originally used escapes methylation, this will involve a corresponding loss in that the cresol ether will not be formed, but this unchanged nitrocresol will be reduced to amino cresol which will remain behind upon steam distillation of the alkaline solution of the aminocresol methyl ether.

f unreduced nitrocresol methyl ether is present after the reduction, this will steam distill with the aminocresol methyl ether, and its presence will lower the melting. point of the product. The reduction should therefore be continued with sufficientof the sulfide until a roduct of appropriate melting point is p need, indicating that the nitro compound has been reduced to the amino compound with substantial completeness. A poduct melting at 45 C. has been found to sufliciently pure for shipment or use; althou h the product maybe further purified w iere a product of increased purity is required.

From the above description it will be seen that the nitrocresol used as the starting material is first subjected to methylation with dimethyl sulfate and alkali, while the nitrocresol methyl other so formed is then subjected to reduction by the addition of the sodium disulfide. The reduction may advantageously follow the methylation, without isolation of the nitrocresol methyl ether, and taking advantage of the hot solution or mixture which is produced by the methylation.

Through the specification and claims it iscresol methyl ether, which comprises su jecting m-mtro-p-cresol methyl ether in admixture with water to reduction by heating with sodium disulfide.

3. The method of producing m-aminocresol methyl ether, which com rises su tote jectin m-mtro-p-cresol to methy ation with dimet yl sulfate and alkali, and subjecting the m-nitro-p-cresol methyl ether thus produced while still hot to reduction b graduall adding a solution of sodium isulfide ueous mixture resulting Irom the methylation.

4. The method of, producing m-nitrocresol methyl ether, which com rises su ect m-mtr -p-cresol to methy ation with dime yl sulfate in the presence of caustic soda and at a regulated temperature of about 40 to C.

5. The method of producing m-aminocresol methyl ether which comprises sub- ]ectmg an aqueous mixture of m-nitropcresol methyl ether to reduction by adually adding thereto a solution of um disulfide, with .regulation of the rate of additron to obtain a vigorous but not violent reaction.

6. The method of roducing m-amino-pcresol methyl ether, which comprises subjecting m-mtrocresolto methylation with dimethyl sul ate and alkali at a regulated temperature of about 40 to 50 C. and subjectmgthe hot ueous mixture so produced to reduction by t e gradual addition thereto of a solution of sodiumdisulfide, and finally recovering the m-amino-p-cresol methyl ether from the reduction product by steam distillation. 4

7. The method of producing m-nitro-pcresol-methyl-ether, which comprises treating m-nitro-p-cresol with dimeth l sulfate in the presence of water and o suflicient aqueous caustic soda to maintain an alkaline reaction throughout the methylation, subjectin the mixture to agitation during the methy ation, and maintaining a regulated temperature below that of boiling of the mixture.

8. The method of producing m-aminocresol-methyl-ether, which comprises su jecting m-nitro-p-cresol to methylation in the resence of an excess of caustic soda, and sub ecting the resulting mixture, while still hot to reduction by adding thereto a sodium sulfide as a reducing agent, and finally recovering the m-amino-p-cresol-methyl-ether from the reduction mixture.

9. In a rocess of making m-nitro-p-cresol methyl etiier b subjecting m-nitro-p-cresol to methylation y means 0 dimethyl sulfate, the step characterized by causing the reaction to occur in the presence of caustic soda in aqueous solution.

10. In a process of making m-nitro-p-cresol methyl ether by the action of dimethyl sulfate on. m-nitro-p-cresol in the presence of caustic soda, the step: which comprise the gradual addition of t e caustic soda, to a mixture of m-nitro-p-cresol and dimethyl sulfate in the presence of water, and maintaining an alkaline reaction in the mixture durin the methylation.

11. he method of producing m-nitro-pcresol methyl ether, which comprises inducing a reaction between m-nitro-p-cresol and dimethyl sulfate in presence of water and caustic soda.

12. The method of producing m-nitro-pcresol methyl ether, which comprises inducing an interaction between one mole each of m-nitro-p-cresol, dimethyl sulfate and canstic soda, in presence of water.

13. The method of producing m-aminocresol methyl ether, which comprises subjecting m-mtro-p-cresol methyl ether to reduction with an alkali metal sulfide in the presence of water.

In testimony whereof, we afiix our signatures.

CLARENCE G. DERICK. THOMAS H. LEAMING. WALTER M. RALPH. 

